1. Field of the Invention
The present invention relates to an apparatus and method for synchronizing audio/video signal and, more particularly, to an apparatus and method for detecting motion of picture when timing difference between audio signal and video signal transmitted occurs and subsequently adjusting a threshold in association with the detected motion of picture, thereby controlling the mute audio signal.
2. Description of the Prior Art
MPEG is a compressed audio/video signal protocol established by the Moving Pictures Experts Group of the International Standardization Organization. One description of MPEG is provided in U.S. Pat. No. 5,621,772 to Greg Maturi et al. entitled Hysteretic Synchronization System For MPEG Audio Frame Decoder.
In general, an audio/video signal is compressed according to an MPEG protocol. According the MPEG protocol, the compressed audio/video signal is segmented into packets for transmission and subsequently the compressed audio signal is time division multiplexed with the compressed video signal.
The associated compressed audio/video signal is not only asynchronous, but their mutual timing relationship or synchronism is nonexistent in transmission.
Accordingly, when an audio/video signal compressed according to an MPEG protocol is decompressed to display on screen, the audio signal must be synchronized with the video signal so that a voice is coincident with a corresponding picture.
A timing difference between the audio and video signals, however, may sometimes occur when the compressed audio/video signal is decompressed. When the timing difference between the audio and video signals occurs, the audio signal should be muted to be in synchronization with video signal so that a voice is coincident with a corresponding picture.
However, decompression in the art is problematic in that it cannot determine the degree of motion of a picture since the mute of the audio signal for synchronization is based on comparison between a previous or subsequent frames to picture, thereby frequently muting the audio signal unnecessarily.